Study Design. Prospective cohort study. Objective. To evaluate whether the DASH is not only a valid and responsive instrument to measure patients with shoulder, arm, and hand complaints, but also to evaluate patients with neck complaints. Summary of Background Data. The DASH has shown to be a valid and responsive questionnaire to evaluate disability in patients with shoulder, arm, and hand complaints. However, patients with shoulder, arm, or hand complaints frequently report neck complaints as well. Therefore, a valid and responsive questionnaire designed for the whole upper extremity, including the neck, would be very useful and practical in upper-extremity research. Methods. Six hundred seventy-nine patients visiting their general practitioner with a new episode of nontraumatic complaints of the neck and upper extremity were evaluated by use of questionnaires at baseline and at 6-months follow-up. Six (sub) groups were formulated according to the location of complaints, including a subgroup with complaints in the shoulder-arm-hand region only and a group with complaints of the neck only. Disability (DASH), general health [SF-12 (physical and mental component)], severity, and persistence of complaints were assessed. Construct validity, floor and ceiling effects, and responsiveness were studied. Results. Correlations between the DASH and the other measures within the 6 (sub) groups at baseline (construct validity), for the change scores at 6-months follow-up (responsiveness), and the responsiveness ratios were classified as acceptable. No floor and ceiling effects were found. Conclusion. The DASH performed well with regard to the a priori hypotheses. This study has shown acceptable validity and responsiveness of the DASH for use in patients with nontraumatic neck complaints in addition to shoulder, arm, and hand complaints. We would caution against using the DASH in patients with neck complaints only, since fewer of the hypotheses could be confirmed in this subgroup.